Silicone oil is blended in many cosmetics as an oil component that gives a refreshing sensation. For example, alkyl-modified silicone (Patent Document 1), fluorine-modified silicone (Patent Document 2), cholesterol-modified silicone (Patent Document 3), acylalkylimine-modified silicone (Patent Document 4), glyceryl-modified silicone (Patent Document 5), alkylglyceryl ether-modified silicone (Patent Document 6), and alkylmonoglyceryl ether-fluorine-modified silicone (Patent Document 7) are blended in cosmetics.
However, since silicone oil gives a strong refreshing sensation and leaves a squeaky sensation of the skin, silicone oil having a texture that feels natural on the skin has been strongly desired.
On the other hand, water-in-oil type emulsified compositions having the oil phase as the outer phase and the water phase as the inner phase are used in various cosmetics. Such water-in-oil type emulsified compositions are, compared with the oil-in-water type, superior in terms of protecting the skin, making the skin supple, and suppressing moisture evaporation from the skin, and therefore are considered to be a suitable formulation for endermic liniments.
Examples of emulsifiers made from a water-in-oil type emulsified composition that have been used traditionally include lipophilic surfactants having a HLB of approximately 1-12, such as polyhydric alcohol fatty acid ester type surfactants such as glycerin fatty acid esters and sorbitan fatty acid esters, as well as polyoxyalkylene-modified organopolysiloxane type surfactants (Non-patent document 1).
However, the water-in-oil type emulsified compositions using these emulsifier have poor emulsification stability and separation between the water phase and the oil phase occurs at high temperatures or over time, making it very difficult to stabilize the formulation.
Also, a method in which wax is blended into the oil phase, i.e. the outer phase, to stabilize the formulation is also being used. However, since wax melts or softens at higher temperatures, there is a problem in that the stability of the formulation is not sufficient. Also, there is a new problem in terms of usability in that spreadability is poor and stickiness occurs at the time of application.
Also, many cosmetics into which powder is blended, such as sunscreens and foundations, require water resistance and/or antiperspiration properties, and therefore hydrophobicized powder is often times blended into a W/O type formulation.
However, when a large quantity of powder is blended into a W/O type formulation, there are problems in that the increased viscosity due to aggregation of powder causes poor spreading at the time of application and the skin turns whiter after the application. To deal with these problems, a technique to more stably disperse powder in an oil agent has been developed.
Technology to primarily disperse powder has been advancing by using miniaturizers such as roller mills, beads mills, and high pressure homogenizers; however, how to keep finely dispersed powder dispersed and free of aggregation for a long time is an issue. Many cosmetics contain silicone oil as an oil component and therefore patents have been filed related to powder dispersing agents using modified silicone. For example, Patent Document 8 uses a powder-in-oil dispersion that uses a dispersing agent prepared by copolymerizing (A) organopolysiloxane monomers and (B) monomers having polylactone-containing groups, hydroxyl groups, or anionic groups. In Patent Document 9, ultraviolet blocking fine particles are dispersed by using a silicone-type dispersing agent composed of modified silicone or reactive silicone.
Patent Document 10 discloses an inorganic powder-in-oil dispersing agent composed of fatty acids to which alkylene oxide is added; dispersibility and stability of POE (4.5) lauryl ether acetic acid, POE (4) stearyl ether acetic acid, POE (10) lauryl ether acetic acid, POE (12) stearyl ether acetic acid, and sodium POE (10) lauryl ether acetate are verified in the examples.    [Patent Document 1] Japanese Patent Laid-Open H5-262616    [Patent Document 2] Japanese Patent Laid-Open H5-247214    [Patent Document 3] Japanese Patent Laid-Open H5-25280    [Patent Document 4] Japanese Patent Laid-Open H5-112423    [Patent Document 5] Japanese Patent Laid-Open H6-157236    [Patent Document 6] Japanese Patent Laid-Open H5-112424    [Patent Document 7] Japanese Patent Laid-Open H9-249518    [Patent Document 8] Japanese Patent Laid-Open H11-263706    [Patent Document 9] Domestic re-publication of PCT international patent publication WO97/45097    [Patent Document 10] Japanese Patent Laid-Open 2000-262883    [Non-Patent Document 1] “Oil Chemistry Handbook—Lipid and Surfactant” 4th edition, 2001, edited by Japan Oil Chemists' Society, Maruzen Corporation